Williams Dual Walll Heater/Pilot goes off

Hi there,
Looks like we have a problem with a Williams Dual wall heater. The heater has been in place for a number of years. Despite numerous attempts to fix the problem, the pilot continues to go out randomly. It may stay on for months at a time, then will simply go off. Once it starts popping off, it is usually not too difficult to relight, but may go off within 10 minutes or an hour. Or, as stated, may stay on for months. Seems most affected in cold weather...
Thanks for any help!
Dennis

What type and where does the flue go? You may need to extend or cap the flue chimney top to prevent a gust of wind from blowing it out. Another possibility is, can you relate when this happens to a particularly cold day or a day when you are using a lot of gas elsewhere in the house? It could be a supply issue that only shows up when lots of other things are using gas.